Astrocytes are the most abundant glial cell type residing in the brain, accounting for 20- 40% of all glial cells. Astrocytes have many important functions, some of which include neurotransmitter uptake and release, modulation of synaptic transmission, and nervous system repair. This webpage covers a background summary of astrocytes, highlights an important astrocytic marker, and the contribution of astrocytes to Amyotrophic Lateral Sclerosis (ALS) and Autism Spectrum Disorders.

Background & GFAP

Amyotrophic Lateral Sclerosis

Autism Spectrum Disorders

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Astrocytes perform many functions. They provide metabolic support to neurons and can rapidly remove excess neurotransmitter (e.g. glutamate) released into the synaptic cleft to protect neurons against neurotoxicity. In addition, astrocytes help maintain brain blood barrier (BBB) integrity and permeability by projecting astrocytic endfeet to encircle and cover endothelial cells of the blood vessels. Similar to microglia, astrocytes are highly sensitive to alterations in their microenvironment, and undergo morphological changes and alter their gene expression profile to upregulate expression and secretion of a variety of bioactive molecules, such as cytokines and chemokines, in response to CNS injury. Furthermore, the function of astrocytes in the maintenance of the BBB has significant implications during inflammation as dysfunction of astrocytes may lead to BBB disruption and favor the infiltration of peripheral immune cells and molecules into the CNS. Astrocytes are macroglial cells in the central nervous system (CNS) and can be identified with markers such as EAAT1/Glast, EAAT2/GLT-1, ALDH1L1, S100β, and Glial Fibrillary Acidic Protein (GFAP).

GFAP is a member of the intermediate filament (IF) family of proteins, and is specifically expressed in astrocytes. IF proteins, together with microtubules and microfilaments, form an interconnected network of the cytoskeleton, which gives cells their form, shape and functions. Astrocytes respond to damage and many disease states resulting in "astrogliosis" or the presence of a "glial response". GFAP antibodies are widely used to detect reactive astrocytes which form part of this response, since reactive astrocytes stain much more strongly with GFAP antibodies than normal astrocytes. GFAP is also a major component of the “glial scar”, an astrocyte rich structure that can inhibit nerve fiber regeneration following damage in the central nervous system. Neural stem cells frequently strongly express GFAP. Antibodies to GFAP are therefore very useful as markers of normal and reactive astrocytic cells and neural stem cells. Visit the Featured Products tab to view a few of our highly specific GFAP antibodies.

Schematic representation of a ‘tripartite synapse’, which refers to the localization of astrocytes in the proximity of synapses. Astrocytes can communicate bi-directionally to relay information to both pre- and post-synaptic structures. This communication is facilitated through the release of gliotransmitters (e.g. glutamate and ATP) from astrocytes. In this figure, glutamate released by neurons is cleared from the synapse and recycled in astrocytes to generate glutamine, which is the essential component of glutamate production at the nerve terminals.